This invention relates to steering systems for tracked vehicles and, more particularly, to a steering system employing a variable hydrodynamic torque converter mechanically coupled via a set of reversing gears to a pair of output shafts, there being a set of externally mounted clutches for selectively engaging individual ones of the reversing gears.
Tracked vehicles, such as digging machines and military tanks are steered by applying a greater speed of track movement to a track on one side of the vehicle as compared to the speed of the track on the opposite side of the vehicle. Typically, the speed differential is imparted by some form of differential gearing system employing clutches for selective activation of gears which drive either the right track or the left track at the greater speed to produce a steering respectively to the left or to the right. Power for operating the steering system has been provided by hydrostatic power units employing a hydraulic piston pump. Variation in the amount of power to accomplish differing amounts of the differential speed of track movement has been accomplished by the use of hydraulic pumps in which the piston displacement may be varied as by use of a well known angled drive plate, wherein the angle of inclination of the drive plate is increased for increased displacement of the piston. For any given linear speed, forward or reverse, of the vehicle, an increase in the differential speed of the tracks decreases the radius of turning, while a decrease in the differential speed of the tracks increases the radius of turning.
A problem arises in that the construction of the foregoing steering system has been unduly expensive, both in terms of initial construction and in terms of maintenance. In addition, a change in turning radius cannot generally be established as readily as is accomplished in the steering of other types of vehicles, such as an automobile.